References

In the real estate sector, citation refers to the documentation and disclosure of the sources of information on which an appraisal, market analysis, property description, or valuation report is based. A thorough list of sources ensures the traceability and verifiability of information-whether regarding comparable prices, market data, structural characteristics, or legal foundations. For expert appraisals, a complete list of sources in accordance with valuation standards (ImmoWertV, HypZert) is mandatory.

Significance in Real Estate Appraisals

Market value appraisals pursuant to Section 194 of the German Building Code (BauGB) and the Real Estate Valuation Ordinance (ImmoWertV 2021) must provide complete documentation of the sources used for comparative data, property interest rates, standard land values, and technical parameters. Typical sources include: purchase price databases from appraisal committees, official standard land values, rent index data, proprietary market surveys, and technical standards (DIN, Eurocodes). A missing or incomplete list of sources can significantly limit the admissibility of an appraisal in court.

The quality of an appraisal depends not least on how current and representative the sources used are. Comparative prices from the appraisal committee’s purchase price database are more meaningful than mere listing data from portals because they reflect actual, notarized transactions and not merely asking prices that are subject to negotiation. Appraisers who rely exclusively on asking prices risk systematic overvaluation-the so-called asking price bias is well documented in German real estate markets and ranges from three to ten percent depending on the segment.

Citation of Sources in Property Listings and Market Reports

Citation of sources is also gaining importance outside of formal appraisals. Real estate agent property descriptions that contain information on rental income, renovation costs, or comparable values should make their sources transparent-both in the interest of due diligence and as a form of consumer protection. Market reports from real estate associations, research institutes, and banks regularly substantiate their claims with source citations, which allow readers to verify the information and demonstrate the report’s credibility.

In the commercial real estate sector, citing sources is a central element of due diligence reviews: Buyers and their advisors verify the origin of the figures cited in the information memorandum and, if necessary, request primary documentation such as lease agreements, operating cost statements, or land registry extracts. Sellers who enter the sales process from the outset with a solid, source-backed dossier accelerate the due diligence process and minimize the risk of price reductions in the final phase.

Citation of Sources and Transparency Requirements

With the growth of digital platforms and AI-powered valuation tools, the question of data origin is gaining importance. Automated valuation models (AVMs) should disclose the transaction databases and algorithms on which they are based. Buyers and lenders have a legitimate interest in knowing whether a valuation is based on actual transaction data or on listing data (which may systematically exceed actual purchase prices).

Source Disclosure and AI-Powered Valuations

With the use of AI-powered valuation models (Automated Valuation Models, AVM) in the real estate industry, source disclosure is taking on a new dimension. Many portals and banks offer automated valuations based on machine learning algorithms-yet often without transparent disclosure of the underlying data and methodology. Buyers and sellers should be aware that such AVM values are reliable only if sufficient transaction data is available for the specific micro-location. In outlying areas of Nuremberg or for atypical properties, AVM values can deviate significantly from actual market prices.

Particular caution is warranted when AVM systems do not disclose their sources or do not report confidence intervals. A point estimate without specifying the underlying data set and statistical uncertainty is ill-suited for serious purchasing and financing decisions. An experienced appraiser can assess whether an AVM value is plausible for the property in question and, if necessary, correct it with a well-founded analysis.

Practical Tip for Property Owners in Nuremberg and Franconia

When you commission an appraisal or receive an offer for your property, you should always ask about the data sources. A reputable appraiser in Nuremberg can explain which comparable properties they used, whether the standard land values from the Nuremberg Appraisal Committee were applied, and what statistical foundations their market analysis is based on. The standard land values for Nuremberg are publicly available via BORISplus.Bayern and provide a transparent, official basis for assessing land values.

We work exclusively with verifiable sources and present our market assessments transparently. Our market price analyses are based on the purchase price collections of the Nuremberg Appraisal Committee, current listing evaluations, and our own transaction data from the metropolitan region-making them significantly more reliable than data from listing portals alone.

Frequently Asked Questions

Where can I find the official standard land values for Nuremberg?

The current standard land values are set by the Appraisal Committee for Property Values in the City of Nuremberg and are publicly available via the Bavarian Standard Land Value Information System (BORISplus.Bayern). They are generally updated every two years.

Can an appraiser use their own comparable transactions from their database?

Yes. Appraisers often build their own databases from their completed appraisals. These can be used as sources if the comparable data is anonymized and applied methodologically correctly. In any case, the type and origin of the comparables must be explained in the appraisal report.

What should I do if a property listing does not cite sources?

Ask for them proactively. Reputable providers will, upon request, disclose where their information on rental income, renovation costs, or comparable prices comes from. If there is no verifiable basis, you should be skeptical and, if in doubt, commission an independent appraisal.

Which sources are most reliable for real estate valuation?

The most reliable sources are notarized purchase prices from the official purchase price database of the Appraisal Committee, as they reflect actual market transactions. Official standard land values come in second place. Listing data from real estate portals is useful as a supplementary market observation, but should generally be discounted, as asking prices are regularly higher than actual transaction prices.

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